XDATA Port

When additional address lines are connected to XDATA-mapped port
lines (?B_MODE = 1) the following configuration settings are
required.

Name

Description

?B_XDATAPORT

Specifies the XDATA memory address used to
select the bank address and defines the address of an external
data port. Any XDATA address can be specified (address range 0H
to 0FFFFH) under which a port can be addressed in the XDATA
area. 0FFFFH is defined as the default value. In this mode,
?B_CURRENTBANK and ?B_XDATAPORT are initialized with the value
0 at the start of the program by the C51 startup code.

?B_FIRSTBIT

Indicates which bit of the defined port is to be
assigned first. Other than ?B_MODE=0, the remaining bits of the
XDATA port cannot be used for other purposes.

Important information

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